Connecting apparatus and method for a precharged refrigeration system

ABSTRACT

Coupling apparatus for a precharged refrigeration system comprising a fusible plug and a valve in lines leading from the precharged portion of the system. When the precharged portion is connected to the balance of the system, the valve is opened to balance the refrigeration pressure across the fusible plug, and heat is applied to melt the plug and establish a refrigerant circuit.

United States Patent 1 Hominid, Jr.

[ May 13, 1975 CONNECTING APPARATUS AND METHOD FOR A PRECI-IARGED REFRIGERATION SYSTEM [75] Inventor: Fred V. Honnold, Jr., North Syracuse, NY.

[73] Assignee: Carrier Corporation, Syracuse, NY.

[22] Filed: June 1, 1973 [21] Appl. No.: 366,226

[52] U.S. Cl. 62/77; 62/292; 62/299 [51] Int. Cl. F25b 45/00 [58] Field of Search 62/299, 292, 77; 137/74 [56] References Cited UNITED STATES PATENTS 2,667,760 2/1954 Curtis 62/299 2,828,759 4/1958 Gerhart 62/299 Primary ExaminerMeyer Perlin Attorney, Agent, or Firm-J. Raymond Curtin [57] ABSTRACT Coupling apparatus for a precharged refrigeration system comprising a fusible plug and a valve in lines leading from the precharged portion of the system. When the precharged portion is connected to the balance of the system, the valve is opened to balance the refrigeration pressure across the fusible plug, and heat is applied to melt the plug and establish a refrigerant circuit.

2 Claims, 1 Drawing Figure CONNECTING APPARATUS AND METHOD FOR A PRECHARGED REFRIGERATION SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to apparatus and a method for connecting a precharged portion of a refrigeration system to the balance of the system.

2. Description of the Prior Art Large refrigeration systems, such as air conditioning systems used for residences and other large interior spaces, are frequently produced as subassemblies and shipped to the installation site for final assembly. Such systems are commonly referred to as "split systems, and include an evaporator unit which is installed inside the residence, and a compressor-condenser unit which is located outside the residence.

Refrigeration systems such as those of the foregoing type, have an optimum charge of refrigerant circulating through the system which effects optimum performance of the system. Thus, precise charging of refrigerant into the system is very important. In addition, the equipment used for charging a refrigeration system with refrigerant is quite complicated and expensive, and requires considerable skill to operate. Therefore, it has become a common practice to precharge the refrigeration system at the factory where the system is manufactured.

Accordingly, split refrigeration systems are frequently manufactured as subassemblies including a condenser-compressor subassembly and an evaporator subassembly. One or both of these subassemblies are precharged at the factory with the proper quantity of refrigerant, and the subassembly is sealed.

A well known means of sealing the precharged portion of a refrigeration system is to incorporate valves in the inlet and outlet lines of that portion. When the precharged portion reaches the installation site, the inlet and outlet lines are connected to corresponding lines of the balance of the system, and the valves are opened to establish a refrigeration circuit. These valves are quite effective, but they are very expensive and are usually used but one time in the normal course of operation of a system namely, to establish the refrigeration circuit when the system is assembled.

Others, recognizing the large expense of incorporating the foregoing valves in refrigeration systems, have suggested the use of fusible plugs in place of the valves. Generally, a portion of a refrigeration system would be precharged at the factory, and a fusible plug would be installed at the inlet and outlet lines of the precharged portion. Heat would be applied to the plugs at the installation site after the refrigeration system was connected, the plugs would melt and the refrigeration circuit would be established. The following U.S. patents are exemplary of the incorporation of fusible plugs in precharged refrigeration systems: U.S. Pat. Nos. 2,782,496; 2,828,759; 2,903,004; 3,139,103; 3,493,002; and 3,539,150. These systems have been found to suffer from one or more of the following disadvantages. First, where a pair of plugs are used to seal the inlet and outlet lines of the precharged portion of the system, the plugs can be blown through the system by virtue of the large pressure differential existing across the plugs at the time that the plugs are melted. Unless provision is made for equalizing the refrigerant pressure across a plug before it is melted, there is a real likelihood of serious damage to the system. Second, complicated devices have been suggested for directing the plug out of the refrigerant flow line after heat has been applied to the plug. Even if such devices are effective in preventing a plug from being blown through the system, the device itself involves an expense which could advantageously be avoided. Third, devices have been suggested for equalizing the pressure across a fusible plug before heat is applied thereto. However, these devices also have proven to be very complicated and very expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a temporary seal for a portion of a refrigeration system for containing a refrigerant charge within that portion.

Another object of the invention is to provide a releasable seal for a precharged refrigeration system which, when released, is not damaging to the system.

A still further object of the invention is to provide improved means and a method for sealing a precharged refrigeration system which are economical yet effective.

Other objects will be apparent from the description to follow and from the appended claims.

The foregoing objects are achieved according to a preferred embodiment of the invention by the provision of a fusible plug in one line of a precharged portion of a refrigeration system, and a valve in the other line of the portion. The precharged portion can be connected to the balance of the refrigeration system, the valve opened to equalize the pressure across the fusible plug, and heat applied to the plug to open that line and to establish a refrigeration circuit in the system.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment of the invention described below, a fusible plug and a valve are provided in the inlet and I outlet lines respectively of a precharged condenser intended for incorporation in a compression refrigeration system. In the precharging process, the plug is sealed in the condenser inlet line and refrigerant is charged into the condenser through the outlet or liquid line valve, and the valve in the liquid line is thereafter closed. When the condenser is coupled to the balance of the refrigeration system in the field, the valve is opened to balance the refrigerant pressure across the fusible plug, and heat is applied to the plug to melt it and to thereby establish a refrigerant circuit in the system.

Referring now to the drawings, a split refrigeration system of the type normally used for the air conditioning of residences is shown. The system includes a condenser 1 which has been precharged with refrigerant at the factory and whose inlet line 3 and outlet line 5 are sealed against refrigerant flow by means of a fusible plug 7 and a valve 9 respectively. Further included in the system are a compressor 11, an evaporator 13, and an expansion device such as a capillary tube or thermal expansion valve 15. A Schraeder valve 17 can be included in the suction line of compressor ll for releasing refrigerant vapor therethrough. The system shown contemplates a commonly housed compressor and condenser unit having a connection 19 forming a part of valve 9 for joining a refrigerant line 21 leading to expansion device 15, and a connection 23 in the suction, line of compressor 11. Similarly, the evaporator unit has a connection 25 on its inlet line for connecting the other end of line 21 to the expansion device which forms part of the evaporator unit, and a connection 27 on its outlet line for receiving the end of refrigerant line 29 coupled to connection 23. The compressorcondenser unit normally has an outdoor installation while the evaporator unit is located within the residence.

Condenser 1 is depicted as a conventional fin-tube condensing unit. Valve 9, in theoutlet line of condenser 1, can be any of a number of conventional refrigeration line valves. Such valves are normally fabricated from a corrosion-resistant material such as brass and include an internal conduit for passing refrigerant through the valve, and a stem for closing that conduit. Valve 9 is shown as including a stem 31 which can be turned with an Allen wrench for selectively opening or closing the valve. Condenser 1 is precharged at the factory with a predetermined quantity of refrigerant through valve 9 in outlet line after fusible plug 7 is installed in line 3 with a sufficient bond to withstand any pressure which would be exerted thereon by the refrigerant in the condenser. Plug 7 can be soldered directly within line 3, or it can be presoldered to a junction line 33 adapted for connection to line 3 and to the discharge line 35 from compressor 11.

The evaporator portion of the system is also often precharged, but with a very light charge of refrigerant, so that removable rubber plugs in the inlet and outlet lines of the evaporator portion will suffice to maintain a charge therein. The condenser-compressor portion of the system and the balance of the system are shipped to the installation site for final connection there. The two portions are placed in their appropriate locations inside and outside the residence, and corresponding refrigerant lines are connected as indicated in FIGJl. Thus, line 21 is connected at its opposite ends to connections 19 and 25, and line 29 is connected to connections 23 and 27. Valve 9 is then opened to allow refrigerant vapor to flow through the system up to fusible plug 7 to equalize the pressure across plug 7. Heat is thereafter applied to the line 33 to melt the plug, and the refrigeration circuit is established.

The use of a fusible plugof the foregoing type greatly reduces the cost of the refrigeration system. A fusible plug generally costs about one tenth of what a conventional brass valve would cost for the inlet line of the condensing unit. By virtue of the equalization ofthe refrigerantpressure acrossthe fusible plug prior to the removal thereof, there is no danger of the plug being blown through the system. v

The invention has been described in detail with particular reference to apreferred embodiment thereof, f but it will be understood that variations and modifica-w tions can be effected within the spirit and scope of the invention.

I claim:

1. A method for connecting a refrigerant-charged" condenser portion of a compression refrigeration sys-Y tem to the balance of the system, the condenser portion having an outlet line .with a fusible sealing plug mounted therein and an inlet line with a valve for selec tively opening and closing the inlet'line to refrigerant/ A flow, and the balance ofthe refrigeration system having 7 corresponding inlet and outlet lines and being substan I tially devoid of condensible contaminants, to establish a refrigerant circuit, said method comprising the steps i a. connecting the inlet and outlet lines of said'con-i denser portion with the corresponding inlet and outlet lines of the balance of the refrigerationsystem;

b. opening the valve in the inlet line to the condenser Q I 1 portion to equalize the refrigerant pressureacross t i the fusible plug; and c. applying heat to the outlet line from the condenser portion to melt the fusible plug and to thereby es tablish a refrigerant circuitin the refrigerationisystern.

densible contaminants, said apparatus comprising:

fusible plug means mounted in one of the inlet; and i. W outlet lines to seal said one line against the flowof refrigerant therethrough; and

valve means for selectively opening or closing the other of said inlet and outlet refrigerant flow lines said valve means being openable after said refrigerant-charged condenser portion is connected to the balance of the system for equalizing the refrigerant pressure across said plug means, and saidplugfl I 7 means being meltable in response to the applica- I tion of heat thereto to establish a refrigerant circuit j I in the system. 

1. A method for connecting a refrigerant-charged condenser portion of a compression refrigeration system to the balance of the system, the condenser portion having an outlet line with a fusible sealing plug mounted therein and an inlet line with a valve for selectively opening and closing the inlet line to refrigerant flow, and the balance of the refrigeration system having corresponding inlet and outlet lines and being substantially devoid of condensible contaminants, to establish a refrigerant circuit, said method comprising the steps of: a. connecting the inlet and outlet lines of said condenser portion with the corresponding inlet and outlet lines of the balance of the refrigeration system; b. opening the valve in the inlet line to the condenser portion to equalize the refrigerant pressure across the fusible plug; and c. applying heat to the outlet line from the condenser portion to melt the fusible plug and to thereby establish a refrigerant circuit in the refrigeration system.
 2. Apparatus for connecting a refrigerant-charged condenser portion of a compression refrigeration system to the balance of the system to establish a refrigerant circuit, the refrigerant-charged condenser portion having inlet and outlet refrigerant lines, and the balance of the system being sUbstantially devoid of condensible contaminants, said apparatus comprising: fusible plug means mounted in one of the inlet and outlet lines to seal said one line against the flow of refrigerant therethrough; and valve means for selectively opening or closing the other of said inlet and outlet refrigerant flow lines; said valve means being openable after said refrigerant-charged condenser portion is connected to the balance of the system for equalizing the refrigerant pressure across said plug means, and said plug means being meltable in response to the application of heat thereto to establish a refrigerant circuit in the system. 